Current research on the families of critically ill adults is limited and none directly addresses the decision-making process of families regarding the withholding or withdrawal of life-sustaining interventions for their family member. Patients in the intensive care unit are frequently rendered unable to make their own decisions due to the seriousness of their illness, or to the use of medications or equipment. If the patient has not provided an advanced directive, the family becomes the surrogate decision maker for the patient. This exploratory study uses in-depth interviews and participant-observation to investigate decision making by families regarding the use of life support. These methods will be used (1) to describe the process of decision making by families, (2) to determine the influence of specific familial relationships and family structure on decision making, (3) to examine the characteristics of the patient (e.g., age, diagnosis, prognosis, length of stay, length of illness, familial relationship, type of life support technology) in relation to the decision making process and outcome, and (4) to assess the effect of nurses' and physicians' communication on family decision making. Family members of critically ill patients requiring decisions about withholding or withdrawal of life support in the Medical Intensive Care Unit at Presbyterian University Hospital will be interviewed. In addition, health care provider/family meetings will be recorded and family members will be observed in the intensive care unit and family waiting room area. Approximately 15 patient cases will be studied. Data from tape recordings of the interviews and meetings, and field notes of observations will be transcribed into a computerized program that assists with systematic coding and categorizing of data. A multidisciplinary research team will systematically review data and identify the factors and interrelationships of factors that give an accurate description of family decision-making. Health care providers need empirical knowledge of family decision making in order to more effectively support and assist families as they deal with decisions regarding the withholding or withdrawal of life sustaining interventions.